Online learning has transformed higher education. Many empirical studies have been done on the challenges with online courses, but few have presented an overview. We reviewed the literature using Cooper's framework. Concerns were found to be common in three large groups: online students, teachers, and people who make materials. Online education had problems because students had different ideas about what was expected of them, their level of preparedness, and their level of engagement. Teachers had to deal with problems like getting used to their new roles in the classroom and having trouble with time management and how to teach. Considerations for content development, the role of instructors in content creation, the use of multimedia in content, the importance of instructional methods, and more came up during this research. Higher education institutions can help both teachers and students get past these problems by giving them opportunities.